Flexible tubing and method of manufacture



Nov, 18, 1969 c. H. OSBORN ET AL 3,478,770

FLEX ISLE TUBING AND METHOD OF MANUFACTURE Filed June 1, 1966 INVENTORS CAR ROLL .OSBORN BY WILSON E. CUDD ATTORN EY United States Patent Office 3,478,770 Patented Nov. 18, 1969 US. Cl. 138-135 8 Claims ABSTRACT OF THE DISCLOSURE Flexible tubing formed of a continuous helical strip having interlocked edges. The stfip is composed of a band of thin flexible material such as plastic, fabric or metal foil, and narrow segments of rigid metal or plastic which are fastened to the edges of the band.

This invention relates to flexible tubing of the type manufactured by continuously forming one or more strips of material and locking them together as they are formed in a helical or spiral direction. The invention further relates to the method of forming such tubing.

It is known in the prior art that flexible tubing may be formed by the so-called strip forniing and interlocking method, and a typical tubing of this type has been disclosed by Rejeski in his Patents Nos. 2,592,335; 2,592,- 336, and 3,085,596. In most of these prior art products, however, the tubing is formed by the formation of a metallic strip which is wound in a spiral form, the edges of this strip being bent in one manner or another while strips of flexible material are inserted between adjacent turns of the strip as it is formed in a helical direction. The resultant product, therefore, is one in which the tubing contains a flexible strip of material extending between two adjacent turns of the metal strip.

Applicants have developed an improved tubing and method in which only a single strip of material is formed in helical turns, this single strip being essentially of flexible material and having a narrow segment or strip of rigid material fastened at each edge thereof. By proper manipulation of the edges, the entire strip is formed so that each adjacent turn will interlock and provide a product which is stronger and at the same time more flexible than those of the prior art. Further, there is the advantage of permitting the manipulation of a single strip of material rather than several strips which makes the operation of forming the tubing somewhat simpler. Finally, the improved method and product permits a stronger interlocking bond for improved sealing and mechanical unity.

It is, therefore, a principal object of the invention to provide flexible tubing which is highlyflexible and has improved strength characteristics. n

It is a further object to provide tubing having an improved seam for better sealing.

It is a further object to provide a simplified production procedure.

These and other objects of the invention will be further understood in the following description and drawings, in which:

FIGURE 1 is a fragmentary perspective view in partial section of a first step in the formation of the strip which comprises the novel tubing.

FIGURE 2 is a similar view illustrating a further step in the formation of this strip.

FIGURE 3 is a similar view illustrating a first step in the interlocking of adjacent turns of the strip in forming the finished tube.

FIGURE 4 is a similar view illustrating a further step in the formation of the tubing.

FIGURE 5 is an elevational view of the finished tubing.

Referring now to the drawings, FIGURE 1 illustrates a portion of a strip 10 which is used to form the novel tubing. This consists of a band or strip of fabric 11 having the width shown in the drawing and extending for an indefinite length. This band may be made of material such as a fabric formed of such fibers as cotton, glass, rayon, nylon, polyester, or any other materials which are usually used in making fabrics; it may be made of a flexible plastic material such as vinyl or similar materials; it may be made of asbestos; it may be made of flexible metal foil such as steel or aluminum; or it may even consist of various combinations such as plastic coated metal foil or fabric; metal coated fabric or plastic materials; or any other combination of materials which provide flexibility. Secured to each edge of the band are narrow segments 12 and 13, made of a rigid material such as thermoplastics, steel or aluminum, and having a thickness of about .030 in. These segments may be of any desired width but should generally each comprise anywhere from 10% to 30% of the overall width of the fabric strip. For example, in utilizing a 5 in. wide band, each segment 12 and 13 may have a width of about /2 in. to 1 /2 in. The segment 12 is adhered along mating surfaces 14 with the band, while the segment 13 is adhered at mating surface 15 with the band by any of many conventional means such as the use of adhesives. In the event the band 11 is metal foil and the segments are metal, it may be possible to utilize seam welding or spot welding for this adhesion.

After the strip 10 is formed in the manner indicated, it is passed through well-known machines which will bend the edges as indicated in FIGURE 2. The left-hand segment 12 together with its adhered portion of the band 11 will be bent upwardly and toward the center at an acute angle and will have a configuration designated by reference numeral 16. The segment 13 and its adhered portion of band 11 will be bent somewhat differently as indicated in FIGURE 2, having an upward obtuse angle away from the center and then terminating in an acute angle in the lower surface of the strip directed toward the center of the strip. This is designated by reference numeral 17. The resultant strip, therefore, is one having the open faces of the bent strips in a direction opposite from each other, but both extending toward the center of the strip. It should be noted that in the event the segments 12 and 13 are made of a thermoplastic material, the ends should be bent while heated to avoid cracking.

FIGURE 3 illustrates the process whereby this strip 10 is formed into the final tubing. This is done by passing the strip over spiral forming heads which are well known in the art to provide a helical or spiral cast to the strip, while the radius of the formed strip is predetermined by the mechanism. By feeding adjacent turns of the strip into the interlocking position shown in FIGURE 3, the edge 16 of each turn is partially interlocked with the edge 17 of the adjacent turn in a continuous manner. As the strip continues through the mechanism, the interlocking is completed as shown in FIGURE 4. The resultant product shown in FIGURE 5 is a flexible tubing 18 in which the interlocking of the adjacent turns provides a seam which is designated by reference numeral 19. It can be seen that this seam incorporates three distinct layers of the band 11 as designated by reference numerals 20, 21 and 22. The innermost layers 20 and 21 are secured between portion 23 of the left-hand segment 12 and portion 24 of the right-hand segment 13. The layer 22 at the same time is secured between portion 24 and portion 25 of the segment 12. An additional portion 26 of the band 11 overlies the portion 25, while outermost of all is still another portion 27 of the band. The resultant seam. is one in which the rigid segments 12 and 13 and the band 11 are completely interlocked for maximum strength, and yet provide a pleasing external appearance because of the fact that the band is outermost of all and provides a continuous elfect. This in itself is a considerable improvement over the prior art in which metal strips are often visibly interspersed between the fabric. The entire tubing structure is highly flexible because of the stretchability and flexibility of the band material which extends between the metal segments. At the same time, each seam provides four layers of interlocked rigid material compared to the normal two layers of the prior art.

The shaping of the rigid segments 12 and 13 described above may apply to metals such as steel or aluminum, in which case these segments are bent into shape just as any metal is cold-formed. However, if the segments are made of a thermoplastic material such as vinyl, polyethylene, or the like, they must be heated so that the bending and the forming into seams can be easily accomplished without cracking or breaking. Only sufficient heat to relieve thermal stresses is necessary.

The configuration illustrated is merely by Way of example and is not intended to be limiting as to other modifications of the invention falling within the scope thereof.

We claim:

1. Flexible tubing formed from a continuous strip of helical turns, said strip comprising a band of thin flexible material and a pair of individual segments of rigid material narrower than said band, said segments secured to the edges only of said band, one edge of each turn interlocked with an edge of an adjacent turn to form a continuous seam incorporating both segments therein.

2. The tubing of claim 1 in which one edge of said strip is bent in a direction opposite to the other edge.

3. The tubing of claim 1 in which said seam includes interlocked multiple layers of said band and said segments.

4. The tubing of claim 1 in which said band is a fabric.

5. The tubing of claim 1 in which said band is a plastic sheet.

'6. The tubing of claim 1 in which said band is a metal foil.

7. The tubing of claim 1 in which said segments are metal.

8. The tubing of claim 1 in which said segments are a thermoplastic.

References Cited UNITED STATES PATENTS 2,337,373 12/1943 Chernack 138-131 2,417,676 3/1947 Chernack 138-131 2,592,335 4/1952 Rejeski 138-135 2,763,292 9/1956 Rejeski 138-131 2,841,183 7/1958 Rejeski 138-135 3,085,596 4/1963 Rejeski 138-131 3,340,901 9/1967 Lombardi 138-135 FOREIGN PATENTS 446,200 1/1948 Canada.

279,036 11/1951 France.

554,977 1/1957 Italy.

HERBERT F. ROSS, Primary Examiner U.S. Cl. X.R. 

